I might be wrong but I don't think that you can. In fact, it wasn't until ME
and 2K when Win32 first provided the DRVM_MAPPER_PREFERRED_GET "message" to
be used with waveInOpen() and waveOutOpen() so that you could determine the
ID of the default device in advance of opening it:

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/devnotes/winpro
g/accessing_the_preferred_device_id.asp

And, _I_ think this is a good thing. The system preferred device is a user
setting. If your application has a preferred device it should salt its id
away somewhere for easy retrieval but it shouldn't mess with global
preferences. Just my opinion, YMMV.

By the way, please post follow-up in the multimedia (mmedia) group.

Regards,
Will